0444: Risk stratification for thromboembolic events in patients with atrial fibrillation and biological valve prosthesis

Abstract

Current ESC guidelines require anticoagulation with VKA in patients with “valvular atrial fibrillation (AF)”, which includes all types of prosthetic valve. We evaluated the value of the CHA 2 DS 2 -VASc score for thromboembolism risk assessment in AF patients with biological valve replacement. Among 8962 patients with AF seen between 2000 and 2010, 8053 (90%) had "non-valvular AF” and 909 (10%) had valvular AF. Patients with valvular AF had a biological prosthesis in 59% (n=549), among which 77% (n=426) had a single aortic prosthesis and 64% (n=309) received a VKA. Patients with aortic bioprosthesis were older and had a higher CHA 2 DS 2 -VASc score than those with a mitral prosthesis or a double valve replacement. During a follow up of 876±1048 days, 681 stroke/thromboembolic events were recorded. The occurrence of events were similar in patients with bioprosthesis compared to the patients without prosthesis: (hazard ratio HR 1.10, 95% CI 0.83-1.45, p=0.52). Patients with aortic bioprosthesis tended to have a higher risk of embolic events vs other AF patients with bioprosthesis (HR 1.73, 95% CI 0.87-3.45), p=0.12). In multivariate analysis, older age and higher CHA 2 DS 2- VASC score were the only predictors of embolic events whilst the presence of a bioprosthesis was not an independent predictor of events. The CHA 2 DS 2 -VASC score predicted the embolism risk in AF patients with a bioprosthesis (c-statistic 0.55 95% CI 0.47-0.63) but was less efficient than in “non-valvular” AF patient (c-statistic 0.66, 95% CI 0.64-0.67). This “real world” results support the use of oral anticoagulation in AF patients who have bioprosthetic heart valves. It also supports the use of CHA 2 DS 2 -VASc scoring for the risk evaluation of AF patients with bioprostheses, albeit with reduced reliability. Patients with aortic bioprosthesis had a non significant higher risk of embolic events. A higher CHA2DS2-VASc score in these patients is likely to explain these results.